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First frost and first measurable snowfall date markets

Every autumn, weather watchers ask when the first freeze or the first measurable snow will arrive. Event contracts turn those questions into dated markets, such as whether a city records 32°F by a given date or sees its first 0.1 inch of snow before the end of the month. The details of station, threshold and reporting decide the result. This SoftCta guide explains what to check.

Frost, freeze and the threshold

In casual use, frost means ice on grass and car windows. Visible frost can form when the official air temperature, measured about six feet above the ground, is several degrees above freezing, because surfaces cool faster on clear, calm nights. Contracts therefore usually settle on a temperature threshold, often 32°F or lower. Some use 28°F, a common definition of a hard freeze. The National Weather Service issues frost advisories and freeze warnings, but those are forecasts and alerts, not settlement data, and criteria vary by office and growing season.

Measurable snow versus a trace

US weather records treat 0.1 inch as the smallest measurable snowfall. A dusting below that is logged as a trace, shown as "T" in climate reports. A market on "first measurable snow" usually does not count a trace, while one on "first snowflakes" would be hard to settle. Our snowfall total guide covers how seasonal totals are measured.

The station matters

Temperatures and snowfall vary across a city. A suburban station may freeze weeks before a downtown one, and an airport by the water may stay milder. Contracts should name a specific station, such as a major airport or Central Park for New York City. Settlement typically relies on the station's daily climate report, which records the day's minimum temperature and snowfall. Our weather verification guide explains the main sources.

Base rates from climate normals

NOAA and local NWS offices publish median first freeze and first snow dates for many stations. These are useful base rates, but the range is wide; first freeze dates can differ by three or four weeks between years. Urban growth and climate trends have pushed some medians later over time. Our guide to base rates and reference classes explains how to use history without leaning on it too hard.

Forecasts close to the date

Within a week or so, ensemble forecasts give a better guide than climatology. A cold, clear, calm night after a front is the classic setup for a first freeze. Our ensemble models guide explains how to read forecast spread.

Wording checks

• Threshold: 32°F, 28°F or 0°C, and whether the reading must be at or below.
• Station: exact station identifier and report type.
• Snow: measurable 0.1 inch or any trace.
• Day boundary: climate reports use local standard time, which can differ from clock time during daylight saving; see our time zone guide.

A reading habit

Note the station's median date, the latest forecast low and the threshold before reacting to a quote. Convert prices with the implied probability tool and verify live prices on the venue.

Primary sources SoftCta readers open

• National Weather Service daily climate reports (CLI) and monthly summaries (CLM)
• NOAA NCEI climate normals and station records
• NWS frost advisory and freeze warning criteria by office
• Local NWS office first freeze and first snow climatology pages

Reading the quote step by step

• Read the full title and rules, including the named settlement source and the time zone.
• Convert the Yes and No prices to implied probabilities and note the gap between them.
• Subtract fees and spread to see the effective price you would actually face.
• Write your own probability range and the evidence behind it, then compare.
• Check related and near-duplicate markets on other venues for consistency.

Closing SoftCta checklist

• Re-read the venue definition in your own words before reacting to a price.
• Convert prices with fee and spread awareness; verify live cents on the operator.
• Prefer primary settlement sources over secondary headlines and social summaries.
• Treat ChanceWire hubs, movers, and tools as orientation — not order entry.
• Confirm age, location, and product eligibility; SoftCta pages will not suggest location spoofing.
• If clarity is incomplete, watching is a complete SoftCta outcome — no pick-selling urgency required.

SoftCta habits

• Write your own probability range before checking the crowd price.
• Prefer dated primary sources over social summaries.
• Compare related markets when a single book looks extreme.
• Size curiosity with fees and depth in mind; substantial risk of loss.